Correlation of the basicity of dipyrrolylmethenes biladienes-a,c with the thermal and kinetic stability of their salts

Advances in the Chemistry of Dipyrrins and Their Complexes

“…Data pertaining to the solvation properties, light absorption spectra, and thermal decomposition values of some dipyrrin hydrobromide salts, bis(dipyrrin) hydrobromide salts, and dipyrrinato metal complexes were reported recently. 3,4,[47][48][49][50] In a study of the antioxidant properties of two bis(dipyrrin)s and several other oligopyrrolic compounds it was shown that the 1,1′-linked bis(dipyrrin), which mimics the linkage of natural linear tetrapyrrolic compounds, exhibited effective antioxidant activity while the unnatural 2,2′-bis(dipyrrin) did not. 51 Free-base dipyrrins are regarded as relatively strong bases.…”

“…52 Deprotonation of dipyrrin hydrobromide salts by organic solvents such as DMF, DMSO, and pyridine has been investigated by spectrophotometric titrations, and these studies showed a correlation between the proton affinity of a dipyrrin and its thermodynamic constant of zinc(II)-ion complexation. 4,49,50 A study regarding the use of 15 N NMR chemical shifts for a series of dipyrrolic molecules including dipyrromethanes, dipyrrins, and dipyrrinato complexes has been reported. 53 The 15 N chemical shifts of the dipyrrolic compounds were found to be difficult to interpret in regard to fine structure but were diagnostic of gross structure concerning the oxidation and complexation states of the dipyrrolic compounds.…”

“…110 The authors proposed that interactions between the ruthenium terpyridine chromophore and the dipyrrinato complex allowed for this first observation of the phenomenon. 110 For the purposes of developing multichromophoric compounds for studying photoinduced electron-transfer reactions, borondifluoride dipyrrinato complexes have been attached to calix [4]arenes 111 but more commonly to metalloporphyrins and porphyrin derivatives. 35,[112][113][114][115][116][117][118][119][120][121][122][123] A further discussion of the application of dipyrrinato complexes in light-harvesting arrays is presented in section 3.1.5.…”

“…Binding of the analyte produces a measurable change in the spectroscopic properties of the borondifluoride dipyrrinato fluorophore. Examples of this strategy include the use of pyridine substituents on borondifluoride dipyrrinato complexes for sensing zinc(II) ions, 36,37,142 zinc(II)bipyridyl substituents for sensing anions, 143 calix [4]arene substituents for sensing calcium(II) ions, 144 hydroxyl-quinoline substituents for sensing mercury(II) ions, 145 benzo crown ether substituents for sensing sodium(I) and potassium(I) ions, 146 azacrown ether substituents for sensing sodium(I) and calcium-(II), 147 an oligothioether substituent for sensing copper(II), 148 a 1,2-diaminophenyl substituent that serves as a probe for nitric oxide, 149 and a phenylboronic acid substituent for sensing monosaccharides. 150 There have been several borondifluoride dipyrrinato complexes developed for sensing pH.…”

“…150 There have been several borondifluoride dipyrrinato complexes developed for sensing pH. The dipyrrin substituent that undergoes chemical changes with changing pH includes a dimethylaminophenyl group, 20,151,152 a phenol, 153 and a calix [4]arene. 154…”